Test criteria
- How do we decide if performance is good or bad?
- For continuous variables,
- usually want to achieve a low sum of squared errors
- equivalently, achieve a high \(R^2\).
\[R^2 = 1 - \frac{\sum (y_i - \hat y_i)^2}{\sum (y_i - \bar{y})^2}\]
- For categorical, can use % accurately classified.